[PATCH v3 0/4] drm/bridge: convert users of of_drm_find_bridge(), part 4

[PATCH v3 0/4] drm/bridge: convert users of of_drm_find_bridge(), part 4

[Luca Ceresoli]

This series converts many DRM drivers from the now deprecated
of_drm_find_bridge() to its replacement of_drm_find_and_get_bridge() which
allows correct bridge refcounting.

This is part of the work to support hotplug of DRM bridges. The grand plan
was discussed in [0].

Here's the work breakdown (➜ marks the current series):

 1. ➜ add refcounting to DRM bridges struct drm_bridge,
      based on devm_drm_bridge_alloc()
    A. ✔ add new alloc API and refcounting (v6.16)
    B. ✔ convert all bridge drivers to new API (v6.17)
    C. ✔ kunit tests (v6.17)
    D. ✔ add get/put to drm_bridge_add/remove() + attach/detach()
         and warn on old allocation pattern (v6.17)
    E. ➜ add get/put on drm_bridge accessors
       1. ✔ drm_bridge_chain_get_first_bridge(), add cleanup action (v6.18)
       2. ✔ drm_bridge_get_prev_bridge() (v6.18)
       3. ✔ drm_bridge_get_next_bridge() (v6.19)
       4. ✔ drm_for_each_bridge_in_chain() (v6.19)
       5. ✔ drm_bridge_connector_init (v6.19)
       6. … protect encoder bridge chain with a mutex
       7. ➜ of_drm_find_bridge
          a. ✔ add of_drm_get_bridge() (v7.0),
	       convert basic direct users (v7.0-v7.1)
	  b. ✔ convert direct of_drm_get_bridge() users, part 2 (v7.0)
	  c. ✔ convert direct of_drm_get_bridge() users, part 3 (v7.0)
	  d. ➜ convert direct of_drm_get_bridge() users, part 4
	       (some v7.1, some pending)
	  e.   convert bridge-only drm_of_find_panel_or_bridge() users
       8. drm_of_find_panel_or_bridge, *_of_get_bridge
       9. ✔ enforce drm_bridge_add before drm_bridge_attach (v6.19)
    F. ✔ debugfs improvements
       1. ✔ add top-level 'bridges' file (v6.16)
       2. ✔ show refcount and list lingering bridges (v6.19)
 2. … handle gracefully atomic updates during bridge removal
    A. ✔ Add drm_dev_enter/exit() to protect device resources (v6.20?)
    B. … protect private_obj removal from list
    C. … Add drm_bridge_clear_and_put()
 3. … DSI host-device driver interaction
 4. ✔ removing the need for the "always-disconnected" connector
 5.   Migrate i.MX LCDIF driver to bridge-connector
 6.   DRM bridge hotplug
    A.   Bridge hotplug management in the DRM core
    B.   Device tree description

[0] https://lore.kernel.org/lkml/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3058@bootlin.com/#t

This work is a continuation of the work to correctly handle bridge
refcounting for existing of_drm_find_bridge(). The ground work is in:

 - commit 293a8fd7721a ("drm/bridge: add of_drm_find_and_get_bridge()")
 - commit 9da0e06abda8 ("drm/bridge: deprecate of_drm_find_bridge()")
 - commit 3fdeae134ba9 ("drm/bridge: add next_bridge pointer to struct drm_bridge")

The whole conversion is split in multiple series to make the review process
a bit smoother:

 - Part 2: mostly drivers in drivers/gpu/drm/bridge [2], applied
 - Part 3: other drivers, low-medium complexity [3], applied
 - Part 4: other drivers, converting the most complex cases [this series]

[2] https://lore.kernel.org/lkml/20260109-drm-bridge-alloc-getput-drm_of_find_bridge-2-v2-0-8bad3ef90b9f@bootlin.com/
[3] https://lore.kernel.org/lkml/20260109-drm-bridge-alloc-getput-drm_of_find_bridge-3-v2-0-8d7a3dbacdf4@bootlin.com/

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
Changes in v3:
- Rebased on current drm-misc-next (on v7.0-rc3)
- Dropped patches already applied
- Link to v2: https://lore.kernel.org/r/20260131-drm-bridge-alloc-getput-drm_of_find_bridge-4-v2-0-e081bcdc1467@bootlin.com

Changes in v2:
- Removed bouncing recipient: Edmund Dea <edmund.j.dea@intel.com>
- used break instead of a warning patch 3, adapted patch 4 as a
  consequence
- Link to v1: https://lore.kernel.org/r/20260116-drm-bridge-alloc-getput-drm_of_find_bridge-4-v1-0-e34b38f50d27@bootlin.com

---
Luca Ceresoli (4):
      drm: renesas: rz-du: rzg2l_du_encoder: convert to of_drm_find_and_get_bridge()
      drm/kmb/dsi: convert to of_drm_find_and_get_bridge()
      drm: rcar-du: encoder: convert to of_drm_find_and_get_bridge()
      drm/omap: dss: convert to of_drm_find_and_get_bridge()

 drivers/gpu/drm/kmb/kmb_dsi.c                     |  2 +-
 drivers/gpu/drm/omapdrm/dss/output.c              | 11 ++++++---
 drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c | 28 ++++++++++++++++++-----
 drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h |  1 +
 drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c     |  2 ++
 drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c  | 14 ++++++++----
 6 files changed, 44 insertions(+), 14 deletions(-)
---
base-commit: 93eb544f1603103ce6be564bceb36e3875ba7ac0
change-id: 20260107-drm-bridge-alloc-getput-drm_of_find_bridge-4-0a92b361fe9d

Best regards,
-- 
Luca Ceresoli <luca.ceresoli@bootlin.com>

[PATCH v3 1/4] drm: renesas: rz-du: rzg2l_du_encoder: convert to of_drm_find_and_get_bridge()

[Luca Ceresoli]

of_drm_find_bridge() is deprecated. Move to its replacement
of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
is put when done.

This is made somewhat simpler by the fact that 'bridge' is a local
variable.

However we need to handle both branches of the main if().

In the 'else' case, just switch to of_drm_find_and_get_bridge() to ensure
the bridge is not freed while in use in the function tail
(drm_bridge_attach() mainly).

In the 'then' case, devm_drm_panel_bridge_add_typed() already increments
the refcount using devres which ties the bridge allocation lifetime to the
device lifetime, so we would not need to do anything. However to have the
same behaviour in both branches take an additional reference here, so that
the bridge needs to be put whichever branch is taken without more
complicated logic. Ensure to clear the bridge pointer however, to avoid
calling drm_bridge_put() on an ERR_PTR.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
 drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
index 5e6dd16705e6..9b65bcefdb86 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
@@ -67,7 +67,7 @@ int rzg2l_du_encoder_init(struct rzg2l_du_device  *rcdu,
 {
 	struct rzg2l_du_encoder *renc;
 	struct drm_connector *connector;
-	struct drm_bridge *bridge;
+	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
 	int ret;
 
 	/*
@@ -83,10 +83,16 @@ int rzg2l_du_encoder_init(struct rzg2l_du_device  *rcdu,
 
 		bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
 							 DRM_MODE_CONNECTOR_DPI);
-		if (IS_ERR(bridge))
-			return PTR_ERR(bridge);
+		if (IS_ERR(bridge)) {
+			// Inhibit the cleanup action on an ERR_PTR
+			ret = PTR_ERR(bridge);
+			bridge = NULL;
+			return ret;
+		}
+
+		drm_bridge_get(bridge);
 	} else {
-		bridge = of_drm_find_bridge(enc_node);
+		bridge = of_drm_find_and_get_bridge(enc_node);
 		if (!bridge)
 			return -EPROBE_DEFER;
 	}

-- 
2.53.0

RE: [PATCH v3 1/4] drm: renesas: rz-du: rzg2l_du_encoder: convert to of_drm_find_and_get_bridge()

[Biju Das]

Hi Luca Ceresoli,

Thanks for the patch.

> -----Original Message-----
> From: Luca Ceresoli <luca.ceresoli@bootlin.com>
> Sent: 18 March 2026 09:40
> Subject: [PATCH v3 1/4] drm: renesas: rz-du: rzg2l_du_encoder: convert to of_drm_find_and_get_bridge()
> 
> of_drm_find_bridge() is deprecated. Move to its replacement
> of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it is put when done.
> 
> This is made somewhat simpler by the fact that 'bridge' is a local variable.
> 
> However we need to handle both branches of the main if().
> 
> In the 'else' case, just switch to of_drm_find_and_get_bridge() to ensure the bridge is not freed
> while in use in the function tail
> (drm_bridge_attach() mainly).
> 
> In the 'then' case, devm_drm_panel_bridge_add_typed() already increments the refcount using devres
> which ties the bridge allocation lifetime to the device lifetime, so we would not need to do anything.
> However to have the same behaviour in both branches take an additional reference here, so that the
> bridge needs to be put whichever branch is taken without more complicated logic. Ensure to clear the
> bridge pointer however, to avoid calling drm_bridge_put() on an ERR_PTR.
> 
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>

Tested on Renesas RZ/V2L SMARC EVK

So,

Tested-by: Biju Das <biju.das.jz@bp.renesas.com>

Cheers,
Biju



> ---
>  drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c b/drivers/gpu/drm/renesas/rz-
> du/rzg2l_du_encoder.c
> index 5e6dd16705e6..9b65bcefdb86 100644
> --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> @@ -67,7 +67,7 @@ int rzg2l_du_encoder_init(struct rzg2l_du_device  *rcdu,  {
>  	struct rzg2l_du_encoder *renc;
>  	struct drm_connector *connector;
> -	struct drm_bridge *bridge;
> +	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
>  	int ret;
> 
>  	/*
> @@ -83,10 +83,16 @@ int rzg2l_du_encoder_init(struct rzg2l_du_device  *rcdu,
> 
>  		bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
>  							 DRM_MODE_CONNECTOR_DPI);
> -		if (IS_ERR(bridge))
> -			return PTR_ERR(bridge);
> +		if (IS_ERR(bridge)) {
> +			// Inhibit the cleanup action on an ERR_PTR
> +			ret = PTR_ERR(bridge);
> +			bridge = NULL;
> +			return ret;
> +		}
> +
> +		drm_bridge_get(bridge);
>  	} else {
> -		bridge = of_drm_find_bridge(enc_node);
> +		bridge = of_drm_find_and_get_bridge(enc_node);
>  		if (!bridge)
>  			return -EPROBE_DEFER;
>  	}
> 
> --
> 2.53.0

[PATCH v3 2/4] drm/kmb/dsi: convert to of_drm_find_and_get_bridge()

[Luca Ceresoli]

of_drm_find_bridge() is deprecated. Move to its replacement
of_drm_find_and_get_bridge() which gets a bridge reference.

This driver has global variables for the DSI host and DSI device, and code
to allocate them on probe but no code to free them when on remove. So it
does not at all support removal, and not even multiple instances. For this
reason putting the reference would be pointless here.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
 drivers/gpu/drm/kmb/kmb_dsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/kmb/kmb_dsi.c b/drivers/gpu/drm/kmb/kmb_dsi.c
index aeb2f9f98f23..febca939bd01 100644
--- a/drivers/gpu/drm/kmb/kmb_dsi.c
+++ b/drivers/gpu/drm/kmb/kmb_dsi.c
@@ -251,7 +251,7 @@ int kmb_dsi_host_bridge_init(struct device *dev)
 		return -EINVAL;
 	}
 	/* Locate drm bridge from the hdmi encoder DT node */
-	adv_bridge = of_drm_find_bridge(encoder_node);
+	adv_bridge = of_drm_find_and_get_bridge(encoder_node);
 	of_node_put(dsi_out);
 	of_node_put(encoder_node);
 	if (!adv_bridge) {

-- 
2.53.0

[PATCH v3 3/4] drm: rcar-du: encoder: convert to of_drm_find_and_get_bridge()

[Luca Ceresoli]

of_drm_find_bridge() is deprecated. Move to its replacement
of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
is put when done.

We need to handle the two cases: when a panel_bridge is added and when it
isn't. So:

 * in the 'else' case a panel_bridge is not added and bridge is found: use
   of_drm_find_and_get_bridge() to get a reference to the found bridge
 * in the 'then' case a panel_bridge is found using a devm function which
   already takes a refcount and will put it on removal, but we need to take
   another so the following code in this function always get exactly one
   reference that it needs to put

In order to put the reference, add the needed drm_bridge_put() calls in the
existing cleanup function.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
 drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c | 28 ++++++++++++++++++-----
 drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h |  1 +
 drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c     |  2 ++
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
index 7ecec7b04a8d..5789fc75092f 100644
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
@@ -51,7 +51,7 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 {
 	struct rcar_du_encoder *renc;
 	struct drm_connector *connector;
-	struct drm_bridge *bridge;
+	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
 	int ret;
 
 	/*
@@ -69,20 +69,26 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 
 		bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
 							 DRM_MODE_CONNECTOR_DPI);
-		if (IS_ERR(bridge))
-			return PTR_ERR(bridge);
+		if (IS_ERR(bridge)) {
+			// Inhibit the cleanup action on an ERR_PTR
+			ret = PTR_ERR(bridge);
+			bridge = NULL;
+			return ret;
+		}
+
+		drm_bridge_get(bridge);
 	} else {
-		bridge = of_drm_find_bridge(enc_node);
+		bridge = of_drm_find_and_get_bridge(enc_node);
 		if (!bridge)
 			return -EPROBE_DEFER;
 
 		if (output == RCAR_DU_OUTPUT_LVDS0 ||
 		    output == RCAR_DU_OUTPUT_LVDS1)
-			rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = bridge;
+			rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = drm_bridge_get(bridge);
 
 		if (output == RCAR_DU_OUTPUT_DSI0 ||
 		    output == RCAR_DU_OUTPUT_DSI1)
-			rcdu->dsi[output - RCAR_DU_OUTPUT_DSI0] = bridge;
+			rcdu->dsi[output - RCAR_DU_OUTPUT_DSI0] = drm_bridge_get(bridge);
 	}
 
 	/*
@@ -135,3 +141,13 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 
 	return drm_connector_attach_encoder(connector, &renc->base);
 }
+
+void rcar_du_encoder_cleanup(struct rcar_du_device *rcdu)
+{
+	int i;
+
+	for (i = 0; i < RCAR_DU_MAX_LVDS; i++)
+		drm_bridge_put(rcdu->lvds[i]);
+	for (i = 0; i < RCAR_DU_MAX_DSI; i++)
+		drm_bridge_put(rcdu->dsi[i]);
+}
diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h
index e5ec8fbb3979..b2b5e93f30f8 100644
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h
@@ -25,5 +25,6 @@ struct rcar_du_encoder {
 int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 			 enum rcar_du_output output,
 			 struct device_node *enc_node);
+void rcar_du_encoder_cleanup(struct rcar_du_device *rcdu);
 
 #endif /* __RCAR_DU_ENCODER_H__ */
diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
index 60e6f43b8ab2..82d16a999ee6 100644
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
@@ -836,6 +836,8 @@ static void rcar_du_modeset_cleanup(struct drm_device *dev, void *res)
 
 	for (i = 0; i < ARRAY_SIZE(rcdu->cmms); ++i)
 		platform_device_put(rcdu->cmms[i]);
+
+	rcar_du_encoder_cleanup(rcdu);
 }
 
 int rcar_du_modeset_init(struct rcar_du_device *rcdu)

-- 
2.53.0

Re: [PATCH v3 3/4] drm: rcar-du: encoder: convert to of_drm_find_and_get_bridge()

[Laurent Pinchart]

Hi Luca,

Thank you for the patch.

On Wed, Mar 18, 2026 at 10:39:37AM +0100, Luca Ceresoli wrote:
> of_drm_find_bridge() is deprecated. Move to its replacement
> of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
> is put when done.
> 
> We need to handle the two cases: when a panel_bridge is added and when it
> isn't. So:
> 
>  * in the 'else' case a panel_bridge is not added and bridge is found: use
>    of_drm_find_and_get_bridge() to get a reference to the found bridge
>  * in the 'then' case a panel_bridge is found using a devm function which
>    already takes a refcount and will put it on removal, but we need to take
>    another so the following code in this function always get exactly one
>    reference that it needs to put
> 
> In order to put the reference, add the needed drm_bridge_put() calls in the
> existing cleanup function.
> 
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> ---
>  drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c | 28 ++++++++++++++++++-----
>  drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h |  1 +
>  drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c     |  2 ++
>  3 files changed, 25 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
> index 7ecec7b04a8d..5789fc75092f 100644
> --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
> +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
> @@ -51,7 +51,7 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
>  {
>  	struct rcar_du_encoder *renc;
>  	struct drm_connector *connector;
> -	struct drm_bridge *bridge;
> +	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
>  	int ret;
>  
>  	/*
> @@ -69,20 +69,26 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
>  
>  		bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
>  							 DRM_MODE_CONNECTOR_DPI);
> -		if (IS_ERR(bridge))
> -			return PTR_ERR(bridge);
> +		if (IS_ERR(bridge)) {
> +			// Inhibit the cleanup action on an ERR_PTR

C-style comments.

Shouldn't drm_bridge_put() be extended to be a no-op when called on an
ERR_PTR ?

> +			ret = PTR_ERR(bridge);
> +			bridge = NULL;
> +			return ret;
> +		}
> +

A comment here would be good.

		/*
		 * The reference taken by devm_drm_panel_bridge_add_typed() is
		 * released automatically. Take a second one for the __free()
		 * when this function will return.
		 */

> +		drm_bridge_get(bridge);
>  	} else {
> -		bridge = of_drm_find_bridge(enc_node);
> +		bridge = of_drm_find_and_get_bridge(enc_node);
>  		if (!bridge)
>  			return -EPROBE_DEFER;
>  
>  		if (output == RCAR_DU_OUTPUT_LVDS0 ||
>  		    output == RCAR_DU_OUTPUT_LVDS1)
> -			rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = bridge;
> +			rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = drm_bridge_get(bridge);

Line wrap.

>  
>  		if (output == RCAR_DU_OUTPUT_DSI0 ||
>  		    output == RCAR_DU_OUTPUT_DSI1)
> -			rcdu->dsi[output - RCAR_DU_OUTPUT_DSI0] = bridge;
> +			rcdu->dsi[output - RCAR_DU_OUTPUT_DSI0] = drm_bridge_get(bridge);

Same.

>  	}
>  
>  	/*
> @@ -135,3 +141,13 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
>  
>  	return drm_connector_attach_encoder(connector, &renc->base);
>  }
> +
> +void rcar_du_encoder_cleanup(struct rcar_du_device *rcdu)
> +{
> +	int i;

i is never negative, make it unsigned.

> +
> +	for (i = 0; i < RCAR_DU_MAX_LVDS; i++)

Use ARRAY_SIZE() here.

> +		drm_bridge_put(rcdu->lvds[i]);
> +	for (i = 0; i < RCAR_DU_MAX_DSI; i++)

Same here.

I have tested the patch and it seems to behave fine.

> +		drm_bridge_put(rcdu->dsi[i]);
> +}
> diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h
> index e5ec8fbb3979..b2b5e93f30f8 100644
> --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h
> +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h
> @@ -25,5 +25,6 @@ struct rcar_du_encoder {
>  int rcar_du_encoder_init(struct rcar_du_device *rcdu,
>  			 enum rcar_du_output output,
>  			 struct device_node *enc_node);
> +void rcar_du_encoder_cleanup(struct rcar_du_device *rcdu);
>  
>  #endif /* __RCAR_DU_ENCODER_H__ */
> diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
> index 60e6f43b8ab2..82d16a999ee6 100644
> --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
> @@ -836,6 +836,8 @@ static void rcar_du_modeset_cleanup(struct drm_device *dev, void *res)
>  
>  	for (i = 0; i < ARRAY_SIZE(rcdu->cmms); ++i)
>  		platform_device_put(rcdu->cmms[i]);
> +
> +	rcar_du_encoder_cleanup(rcdu);
>  }
>  
>  int rcar_du_modeset_init(struct rcar_du_device *rcdu)
> 

-- 
Regards,

Laurent Pinchart

Re: [PATCH v3 3/4] drm: rcar-du: encoder: convert to of_drm_find_and_get_bridge()

[Luca Ceresoli]

Hi Laurent,

On Wed Mar 18, 2026 at 4:25 PM CET, Laurent Pinchart wrote:
> Hi Luca,
>
> Thank you for the patch.
>
> On Wed, Mar 18, 2026 at 10:39:37AM +0100, Luca Ceresoli wrote:
>> of_drm_find_bridge() is deprecated. Move to its replacement
>> of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
>> is put when done.
>>
>> We need to handle the two cases: when a panel_bridge is added and when it
>> isn't. So:
>>
>>  * in the 'else' case a panel_bridge is not added and bridge is found: use
>>    of_drm_find_and_get_bridge() to get a reference to the found bridge
>>  * in the 'then' case a panel_bridge is found using a devm function which
>>    already takes a refcount and will put it on removal, but we need to take
>>    another so the following code in this function always get exactly one
>>    reference that it needs to put
>>
>> In order to put the reference, add the needed drm_bridge_put() calls in the
>> existing cleanup function.
>>
>> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
>> ---
>>  drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c | 28 ++++++++++++++++++-----
>>  drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h |  1 +
>>  drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c     |  2 ++
>>  3 files changed, 25 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
>> index 7ecec7b04a8d..5789fc75092f 100644
>> --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
>> +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
>> @@ -51,7 +51,7 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
>>  {
>>  	struct rcar_du_encoder *renc;
>>  	struct drm_connector *connector;
>> -	struct drm_bridge *bridge;
>> +	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
>>  	int ret;
>>
>>  	/*
>> @@ -69,20 +69,26 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
>>
>>  		bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
>>  							 DRM_MODE_CONNECTOR_DPI);
>> -		if (IS_ERR(bridge))
>> -			return PTR_ERR(bridge);
>> +		if (IS_ERR(bridge)) {
>> +			// Inhibit the cleanup action on an ERR_PTR
>
> C-style comments.

OK

> Shouldn't drm_bridge_put() be extended to be a no-op when called on an
> ERR_PTR ?

Uhm, maybe, even though I think I haven't encountered many cases like this
where this was troublesome, and all those I can remember are related to
panel_bridge functions that are meant to be reworked.

Also, drm_bridge_put() deliberately mimicks of_node_put() which also checks
for NULL but not for IS_ERR.

Maxime, your opinion about Laurent's suggestion?

>> +			ret = PTR_ERR(bridge);
>> +			bridge = NULL;
>> +			return ret;
>> +		}
>> +
>
> A comment here would be good.
>
> 		/*
> 		 * The reference taken by devm_drm_panel_bridge_add_typed() is
> 		 * released automatically. Take a second one for the __free()
> 		 * when this function will return.
> 		 */

Sure, makes sense. I'll add one to other patches of this series where
relevant.

>
>> +		drm_bridge_get(bridge);
>>  	} else {
>> -		bridge = of_drm_find_bridge(enc_node);
>> +		bridge = of_drm_find_and_get_bridge(enc_node);
>>  		if (!bridge)
>>  			return -EPROBE_DEFER;
>>
>>  		if (output == RCAR_DU_OUTPUT_LVDS0 ||
>>  		    output == RCAR_DU_OUTPUT_LVDS1)
>> -			rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = bridge;
>> +			rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = drm_bridge_get(bridge);
>
> Line wrap.

I wish the 80-VS-100 policy were clear and valid for all the kernel. But no
big deal here, and you maintain this driver, so I'll split.

> I have tested the patch and it seems to behave fine.

thanks for reviewing and testing!

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[PATCH v3 4/4] drm/omap: dss: convert to of_drm_find_and_get_bridge()

[Luca Ceresoli]

of_drm_find_bridge() is deprecated. Move to its replacement
of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
is put when done.

omapdss_device_init_output() can take one bridge pointer in out->bridge or
two pointers in out->bridge and out->next_bridge. Ensure each has a
corresponding drm_bridge_get() and add drm_bridge_put() calls in the
cleanup code.

Also slightly change the initial code assigning out->panel and out->bridge
to ensure and clarify that either out->panel or out->bridge is set in the
function prologue, not both. If both were set, the 'if (out->panel){...}'
code that follows would overwrite out->bridge without having put the
reference.

Finally, take a reference in case a panel_bridge is added using
drm_panel_bridge_add(). This ensures we always need to put a reference,
which came either from of_drm_find_and_get_bridge() or by the
drm_panel_bridge_add+drm_bridge_get() branch.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
 drivers/gpu/drm/omapdrm/dss/output.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/dss/output.c b/drivers/gpu/drm/omapdrm/dss/output.c
index 7378e855c278..ca891aba3820 100644
--- a/drivers/gpu/drm/omapdrm/dss/output.c
+++ b/drivers/gpu/drm/omapdrm/dss/output.c
@@ -30,11 +30,13 @@ int omapdss_device_init_output(struct omap_dss_device *out,
 		return 0;
 	}
 
-	out->bridge = of_drm_find_bridge(remote_node);
 	out->panel = of_drm_find_panel(remote_node);
 	if (IS_ERR(out->panel))
 		out->panel = NULL;
 
+	if (!out->panel)
+		out->bridge = of_drm_find_and_get_bridge(remote_node);
+
 	of_node_put(remote_node);
 
 	if (out->panel) {
@@ -49,7 +51,7 @@ int omapdss_device_init_output(struct omap_dss_device *out,
 			goto error;
 		}
 
-		out->bridge = bridge;
+		out->bridge = drm_bridge_get(bridge);
 	}
 
 	if (local_bridge) {
@@ -59,7 +61,7 @@ int omapdss_device_init_output(struct omap_dss_device *out,
 		}
 
 		out->next_bridge = out->bridge;
-		out->bridge = local_bridge;
+		out->bridge = drm_bridge_get(local_bridge);
 	}
 
 	if (!out->bridge) {
@@ -79,6 +81,9 @@ void omapdss_device_cleanup_output(struct omap_dss_device *out)
 	if (out->bridge && out->panel)
 		drm_panel_bridge_remove(out->next_bridge ?
 					out->next_bridge : out->bridge);
+
+	drm_bridge_put(out->next_bridge);
+	drm_bridge_put(out->bridge);
 }
 
 void dss_mgr_set_timings(struct omap_dss_device *dssdev,

-- 
2.53.0